We normally go in for thin and streamlined wallets 'round this blog, but Scottish researchers suggests a (cute) baby photo is a seriously worthy addition to any wallet. It might just pressure your billfold's finder into mailing it your way.

Psychologists in Edinburgh left 240 test wallets "lost" around city streets last year, each containing a mailing address that a good Samaritan could act on. In the plastic photo frame of equal numbers of wallets, pictures of "a smiling baby, a cute puppy, a happy family or a contented elderly couple" were inserted, or no image was left at all. Some wallets also contained papers indicating the owner had recently donated to charity.

So, what happened?

The baby photograph wallets had the highest return rate, with 88 per cent of the 40 being sent back. Next came the puppy, the family and the elderly couple, with 53 per cent, 48 and 28 respectively. At 20 per cent and 15, the charity card and control wallets had the lowest return rates.

It's worth noting that 42 percent of all the wallets were returned, a higher number than the research team, or most hardened urbanites, would expect. The baby photographs, however, may have added extra motivation by triggering an evolutionary compassion toward "vulnerable infants," which the study's psychologists cite as the underlying factor in those wallets' higher return rates.

The takeaway? If your wallet's got a photo frame not getting any real use (for the time being, at least), consider stocking it with the best result from a photo search for adorable | "cute as a button" | precious. It might just tip your finder toward empathy, and you'll at least have a clever explanation when your friends find it.